ALKALOIDS 



365 



merely to show the skeleton formulae of a member of each 

 group :— 



}^ 



CH, 



N 



Papaverine 



Morphine * 



Berberine 



In addition to the alkaloids mentioned above, there are 

 a very large number which cannot as yet be classified, since 

 their constitution is not entirely known ; these include amongst 

 others ergotinine from ergot, colchicine from Colchicum, taxine 

 from Taxus haccata, aconitine from Aconitum Napellus, del- 

 phinine from Delphinium, etc. 



GENERAL PROPERTIES OF ALKALOIDS. 



The alkaloids are, as a rule, composed of the four elements, 

 carbon, hydrogen, nitrogen, and oxygen, but a few are known, 

 such as coniine, nicotine, and one or two little-known ones, 

 such as hymenodictine and conessine (from bark of Wrightia 

 antidysenterica) , which contain no oxygen. 



There are a few alkaloids which are liquid, e.g., coniine, 

 nicotine, pelletierine, sparteine, etc., but by far the greater 

 number are colourless crystalline solids. They are, as a rule, 

 insoluble in water, but dissolve in neutral organic solvents, 

 such as ether, amyl alcohol, chloroform, carbon tetrachloride, 

 etc., whereas their salts have just the opposite solubilities. 



They are mostly free from smell, but coniine, nicotine, 

 and sparteine have strong odours. 



Most of them have a bitter taste and are possessed of 

 marked physiological or toxic properties. 



They are all bases, and accordingly have an alkaline 

 reaction in solution, though it must be borne in mind that 



* This formula is subject to revision. 



